Beginning Networking What is Networking? Lets go see!
Networking Terms (the short list) • A network adapterinterfaces a computer to a network. The term "adapter" was popularized originally by Ethernet add-in cards for PCs. Modern network adapter hardware exists in several forms. Traditional Ethernet adapters for desktop PCs were PCI cards. PCMCIA (also know as "credit card" or "PC Card") adapters or similar devices that connected to USB ports were more commonly used in laptop computers. Nowadays, though, both Ethernet and wireless network adapters are simply integrated circuit chips pre-installed inside the computer. • Windows and other operating systems support both wired and wireless network adapters through a piece of software called a device driver. Network drivers allow application software to communicate with the adapter hardware. Network device drivers are often installed automatically when adapter hardware is first powered on. • Finally, some network adapters are purely software packages that simulate the functions of a network card. These so-called virtual adapters are especially common in virtual private networking (VPN) software systems. • Also Known As: NIC, LAN card
Networking Terms (the short list) • A network address serves as a unique identifier for a computer on a network. When set up correctly, computers can determine the addresses of other computers on the network and use these addresses to send messages to each other.One of the best known form of network addressing is the Internet Protocol (IP) address. IP addresses consist of four bytes (32 bits) that uniquely identify all computers on the public Internet. • Another popular form of address is the Media Access Control (MAC) address. MAC addresses are six bytes (48 bits) that manufacturers of network adapters burn into their products to uniquely identify them.
Networking Terms (the short list) • ADSL is a type of Digital Subscriber Line (DSL) Internet service commonly used in homes. The 'A' in ADSL refers to its asymmetry: ADSL connections provide comparatively more bandwidth for downloads than for uploads.ADSL is designed to support the typical home user who frequently downloads large amounts of data from Web sites and P2P networks but upload relatively less often. ADSL works by allocating a majority of the available phone line frequencies for communication of downstream traffic. • In other respects, ADSL possesses all of the characteristics one associates with DSL, including "high-speed" service, an "always on" combination of voice and data support, and availability and performance that is limited by physical distance. ADSL is technically capable of up to 6 Mbps (roughly 6000 Kbps), but ADSL customers in practice obtain 2 Mbps or lower for downloads and up to 512 Kbps for uploads. • Also Known As: Asymmetric Digital Subscriber Line
Networking Term (the short List) • Wireless access points(APs or WAPs) are specially configured nodes on wireless local area networks (WLANs). Access points act as a central transmitter and receiver of WLAN radio signals.Access points used in home or small business networks are generally small, dedicated hardware devices featuring a built-in network adapter, antenna, and radio transmitter. Access points support Wi-Fi wireless communication standards. • Although very small WLANs can function without access points in so-called "ad hoc" or peer-to-peer mode, access points support "infrastructure" mode. This mode bridges WLANs with a wired Ethernet LAN and also scales the network to support more clients. Older and base model access points allowed a maximum of only 10 or 20 clients; many newer access points support up to 255 clients.
Networking terms (the short list) • On wireless computer networks, ad-hocmode is a method for wireless devices to directly communicate with each other. Operating in ad-hoc mode allows all wireless devices within range of each other to discover and communicate in peer-to-peer fashion without involving central access points (including those built in to broadband wireless routers).To set up an ad-hoc wireless network, each wireless adapter must be configured for ad-hoc mode versus the alternative infrastructure mode. In addition, all wireless adapters on the ad-hoc network must use the same SSID and the same channel number. • An ad-hoc network tends to feature a small group of devices all in very close proximity to each other. Performance suffers as the number of devices grows, and a large ad-hoc network quickly becomes difficult to manage. Ad-hoc networks cannot bridge to wired LANs or to the Internet without installing a special-purpose gateway. • Ad hoc networks make sense when needing to build a small, all-wireless LAN quickly and spend the minimum amount of money on equipment. Ad hoc networks also work well as a temporary fallback mechanism if normally-available infrastructure mode gear (access points or routers) stop functioning.
Networking Terms (the short list) • Bandwidthin computer networking refers to the data rate supported by a network connection or interface. One most commonly expresses bandwidth in terms of bits per second (bps). The term comes from the field of electrical engineering, where bandwidth represents the total distance or range between the highest and lowest signals on the communication channel (band).Bandwidth represents the capacity of the connection. The greater the capacity, the more likely that greater performance will follow, though overall performance also depends on other factors, such as latency. • Also Known As: throughput
Networking Terms (the short list) • The term broadband refers to any type of transmission technique that carries several data channels over a common wire. DSL service, for example, combines separate voice and data channels over a single telephone line. In DSL, voice fills the low end of the frequency spectrum and data fills the high end.In home networking, broadband constitutes any form of high-speed Internet access using this transmission technique. Both DSL and cable modem are common broadband Internet technologies. So-called broadband routers and broadband modems are network devices that support both DSL and cable. Other forms of home broadband include fiber (FTTH) and fixed wireless. • To qualify as a broadband Internet service, the technology should as a general guideline support network bandwidth of at least 256 Kbps for connections in one direction.
Networking Terms (the short list) • A broadband modemis a type of digital modem used with high-speed DSL or cable Internet service. Cable modems connect a home computer (or network of home computers) to residential cable TV service, while DSL modems connect to residential public telephone service.Like the television "set top" box, both cable and DSL modems are normally supplied by the Internet service provider and not a piece of equipment individuals need to shop for on their own. • Most broadband modems supply a 10 MbpsEthernet connection for the home LAN, although broadband Internet services rarely if ever perform at those speeds. The performance of a cable modem can vary depending on the utilization of the shared cable line in that neighborhood, and DSL modem speeds also vary, but typical data rates range anywhere from 500 Kbps to 3500 Kbps. • Also Known As: cable modem, DSL modem
Networking Terms ( the short list) • CAT5(also, CAT 5) is an Ethernet network cable standard defined by the Electronic Industries Association and Telecommunications Industry Association (commonly known as EIA/TIA). CAT5 is the fifth generation of twisted pair Ethernet technology and the most popular of all twisted pair cables in use today.CAT5 cable contains four pairs of copper wire. It supports Fast Ethernet speeds (up to 100 Mbps). As with all other types of twisted pair EIA/TIA cabling, CAT5 cable runs are limited to a maximum recommended run length of 100m (328 feet). • Although CAT5 cable usually contains four pairs of copper wire, Fast Ethernet communications only utilize two pairs. A newer specification for CAT5 cable - CAT5 enhanced ("CAT5e" or "CAT 5e") - supports networking at Gigabit Ethernet[ speeds (up to 1000 Mbps) over short distances by utilizing all four wire pairs, and it is backward-compatible with ordinary CAT5. • Twisted pair cable like CAT5 comes in two main varieties, solid and stranded. Solid CAT5 cable supports longer length runs and works best in fixed wiring configurations like office buildings. Stranded CAT5 cable, on the other hand, is more pliable and better suited for shorter-distance, movable cabling such as on-the-fly patch cabling.
Networking Terms (The Short list) • CAT6is an Ethernet cable standard defined by the Electronic Industries Association and Telecommunications Industry Association (commonly known as EIA/TIA). CAT6 is the sixth generation of twisted pair Ethernet cabling.CAT6 cable contains four pairs of copper wire like the previous generation CAT5. Unlike CAT5, however, CAT6 fully utilizes all four pairs. CAT6 supports Gigabit Ethernet speeds up to 1 gigabit per second (Gbps) and supports communications at more than twice the speed of CAT5e, the other popular standard for Gigabit Ethernet cabling. An enhanced version of CAT6 called CAT6a supports up to 10 Gbps speeds. • As with all other types of twisted pair EIA/TIA cabling, individual CAT6 cable runs are limited to a maximum recommended length of 100m (328 feet). Printing along the length of the cable sheath identifies it as CAT6.
Networking Terms (The Short List) • A crossover cabledirectly connects two network devices of the same type to each other over Ethernet. Ethernet crossover cables are commonly used when temporarily networking two devices in situations where a network router, switch or hub is not present.Compared to standard Ethernet cables, the internal wiring of Ethernet crossover cables reverses the transmit and receive signals. The reversed color-coded wires can be seen through the RJ-45 connectors at each end of the cable: • Standard cables have an idential sequence of colored wires on each end • Crossover cables have the 1st and 3rd wires (counting from left to right) crossed, and the 2nd and 6th wires crossed • An Ethernet crossover cable will also feature the name "crossover" stamped on its packaging and wire casing.Ethernet crossover cables should only be used for direct network connections. In particular, attempting to connect a computer to a hub with a crossover cable will prevent that network link from functioning. Home broadband routers have become an exception to this rule: modern consumer routers contain logic to automatically detect crossover cables and allow them to function with other types of Ethernet devices.
Networking terms (the short List) • DHCP allows a computer to join an IP-based network without having a pre-configured IP address. DHCP is a protocol that assigns unique IP addresses to devices, then releases and renews these addresses as devices leave and re-join the network. Internet service providers usually use DHCP to help customers join their networks with minimum setup effort required. Likewise, home network equipment like broadband routers offers DHCP support for added convenience in joining home computers to local area networks (LANs). • DHCP environments require a DHCP server set up with the appropriate configuration parameters for the given network. Key DHCP parameters include the range or "pool" of available IP addresses, the correct subnet masks, plus network gateway and name server addresses. • Devices running DHCP client software can then automatically retrieve these settings from DHCP servers as needed. DHCP clients are built into all common network operating systems. Using DHCP on a network means system administrators do not need to configure these parameters individually for each client device. • Also Known As: Dynamic Host Configuration Protocol
Networking Terms (The short List) • The DNS translates Internet domain and host names to IP addresses. DNS automatically converts the names we type in our Web browser address bar to the IP addresses of Web servers hosting those sites.DNS implements a distributed database to store this name and address information for all public hosts on the Internet. DNS assumes IP addresses do not change (are statically assigned rather than dynamically assigned). • The DNS database resides on a hierarchy of special database servers. When clients like Web browsers issue requests involving Internet host names, a piece of software called the DNS resolver (usually built into the network operating system) first contacts a DNS server to determine the server's IP address. If the DNS server does not contain the needed mapping, it will in turn forward the request to a different DNS server at the next higher level in the hierarchy. After potentially several forwarding and delegation messages are sent within the DNS hierarchy, the IP address for the given host eventually arrives at the resolver, that in turn completes the request over Internet Protocol. • DNS additionally includes support for caching requests and for redundancy. Most network operating systems support configuration of primary, secondary, and tertiary DNS servers, each of which can service initial requests from clients. Internet Service Providers (ISPs) maintain their own DNS servers and use DHCP to automatically configure clients, relieving most home users of the burden of DNS configuration. • Also Known As: Domain Name System, Domain Name Service, Domain Name Server
Network Terms (The Short List) • DDNS (Dynamic DNS) is a service that maps Internet domain names to IP addresses. DDNS serves a similar purpose to DNS: DDNS allows anyone hosting a Web or FTP server to advertise a public name to prospective users.Unlike DNS that only works with static IP addresses, DDNS is designed to also support dynamic IP addresses, such as those assigned by a DHCP server. That makes DDNS a good fit for home networks, which often receive dynamic public IP addresses from their Internet provider that occasionally change. • To use DDNS, one simply signs up with a DDNS provider and installs network software on their host to monitor its IP address. For example, dyndns.com provides a free dynamic DDNS service via software that can run on Windows, Mac or Linux computers. • Compared to ordinary DNS, the disadvantage of DDNS is that additional host software, a new potential failure point on the network, must be maintained. • Also Known As: dynamic DNS
Networking Terms (The Short List) • In computer networking, a dongle is a short length of cable designed to bridge between two devices having different connector types.Dongles first became popular in home networking for connecting to the PCMCIA "credit card" network adapters in older laptop computers. One end of the dongle fit the thin PCMCIA connector while the other end featured either a RJ-45 connector (for connecting an Ethernet cable) or an RJ-11 connector (for connecting to a phone line and dialup Internet access). • Today, dongles continue to be widely used in wired network setups, particular for connections to USB ports on computers. Dongle cables typically run no longer than about six inches (15 cm). • Pronunciation: DONG-ul
Networking Terms (The Short List) • Ethernet is a physical and data link layer technology for local area networks (LANs). Ethernet was invented by engineer Robert Metcalfe.When first widely deployed in the 1980s, Ethernet supported a maximum theoretical data rate of 10 megabits per second (Mbps). Later, so-called "Fast Ethernet" standards increased this maximum data rate to 100 Mbps. Today, Gigabit Ethernet technology further extends peak performance up to 1000 Mbps. • Higher level network protocols like Internet Protocol (IP) use Ethernet as their transmission medium. Data travels over Ethernet inside protocol units called frames. • The run length of individual Ethernet cables is limited to roughly 100 meters, but Ethernet networks can be easily extended to link entire schools or office buildings using network bridge devices.
Networking Terms (The Short List) • A network firewallprotects a computer network from unauthorized access. Network firewalls may be hardware devices, software programs, or a combination of the two. Network firewalls guard an internal computer network (home, school, business intranet) against malicious access from the outside. Network firewalls may also be configured to limit access to the outside from internal users. • Network Firewalls and Broadband Routers • Many home network router products include built-in firewall support. The administrative interface of these routers include configuration options for the firewall. Router firewalls can be turned off (disabled), or they can be set to filter certain types of network traffic through so-called firewall rules.Network Firewalls and Proxy Servers • Another common form of network firewall is a proxy server. Proxy servers act as an intermediary between internal computers and external networks by receiving and selectively blocking data packets at the network boundary. These network firewalls also provide an extra measure of safety by hiding internal LAN addresses from the outside Internet. In a proxy server firewall environment, network requests from multiple clients appear to the outsider as all coming from the same proxy server address. • Also Known As: proxy, gateway
Networking Terms (The Short List) • FTP allows you to transfer files between two computers on the Internet. FTP is a simple network protocol based on Internet Protocol and also a term used when referring to the process of copying files when using FTP technology.To transfer files with FTP, you use a program often called the "client." The FTP client program initiates a connection to a remote computer running FTP "server" software. After the connection is established, the client can choose to send and/or receive copies of files, singly or in groups. To connect to an FTP server, a client requires a username and password as set by the administrator of the server. Many public FTP archives follow a special convention for that accepts a username of "anonymous." • Simple FTP clients are included with most network operating systems, but most of these clients (such as FTP.EXE on Windows) support a relatively unfriendly command-line interface. Many alternative freeware / shareware third-party FTP clients have been developed that support graphic user interfaces (GUIs) and additional convenience features. In any FTP interface, clients identify the FTP server either by its IP address (such as 192.168.0.1) or by its host name (such as ftp.about.com). • FTP supports two modes of data transfer: plain text (ASCII), and binary. You set the mode in the FTP client. A common error when using FTP is attempting to transfer a binary file (such as a program or music file) while in text mode, causing the transfered file to be unusable. • Also Known As: File Transfer Protocol
Networking Terms (The Short List) • A network gatewayis an internetworking system capable of joining together two networks that use different base protocols. A network gateway can be implemented completely in software, completely in hardware, or as a combination of both. Depending on the types of protocols they support, network gateways can operate at any level of the OSI model. Because a network gateway, by definition, appears at the edge of a network, related capabilities like firewalls tend to be integrated with it. On home networks, a broadband router typically serves as the network gateway although ordinary computers can also be configured to perform equivalent functions.
Networking Terms (The Short List) • In computer networking, a kilobitnormally represents 1000 bits of data. Amegabitrepresents 1000 kilobits and agigabitrepresents 1000 megabits (equal to one million kilobits).Kilobits, megabits and gigabits traveling over a computer network are typically measured per second. One kilobit per second equals 1 Kbps or kbps (these are equivalent), one megabit 1 Mbps, and one gigabit 1 Gbps. Slow network connections such as modem links are measured in kilobits, faster links such as WiFi wireless in megabits, and very fast connections like high-speed Ethernet in gigabits. • Many people less familiar with computer networking believe one kilobit equals 1024 bits. This is generally untrue in networking but may be true in other contexts. Specifications for today's adapters, routers and other networking equipment always use 1000-bit kilobits as the basis of their quoted data rates. The confusion arises as computer memory and disk drive manufacturers often use 1024-byte kilobytes as the basis of their quoted capacities.
Networking Terms (The Short List) • HTTP- the Hypertext Transfer Protocol - provides a standard for Web browsers and servers to communicate. The definition of HTTP is a technical specification of a network protocol that software must implement.HTTP is an application layer network protocol built on top of TCP. HTTP clients (such as Web browsers) and servers communicate via HTTP request and response messages. The three main HTTP message types are GET, POST, and HEAD. • HTTP utilizes TCP port 80 by default, though other ports such as 8080 can alternatively be used. • The current version of HTTP in widespread use - HTTP version 1.1 - was developed to address some of the performance limitations of the original version - HTTP 1.0. HTTP 1.1 is documented in RFC 2068. • Also Known As: HyperText Transfer Protocol
Networking Terms (The Short List) • Definition: In computer networking, a hub is a small, simple, inexpensive device that joins multiple computers together. Many network hubs available today support the Ethernet standard. Other types including USB hubs also exist, but Ethernet is the type traditionally used in home networking.Working With Ethernet Hubs • To network a group of computers using an Ethernet hub, first connect an Ethernet cable into the unit, then connect the other end of the cable to each computer's network interface card (NIC). All Ethernet hubs accept the RJ-45 connectors of standard Ethernet cables.To expand a network to accommodate more devices, Ethernet hubs can also be connected to each other, to switches, or to routers. • Characteristics of Ethernet Hubs • Ethernet hubs vary in the speed (network data rate or bandwidth) they support. Some years ago, Ethernet hubs offered only 10 Mbps rated speeds. Newer types of hubs offer 100 Mbps Ethernet. Some support both 10 Mbps and 100 Mbps (so-called dual-speed or 10/100 hubs).The number of ports an Ethernet hub supports also varies. Four- and five-port Ethernet hubs are most common in home networks, but eight- and 16-port hubs can be found in some home and small office environments. • Older Ethernet hubs were relatively large in size and sometimes noisy as they contained built in fans for cooling the unit. Newer devices are much smaller, designed for mobility, and noiseless. • When To Use an Ethernet Hub • Ethernet hubs operate as Layer 2 devices in the OSI model, the same as network switches. Although offering comparable functionality, nearly all mainstream home network equipment today utilizes network switch technology instead of hubs due to the performance benefits of switches. A hub can be useful for temporarily replacing a broken network switch or when performance is not a critical factor on the network.
Networking Terms (The Short List) • IP (Internet Protocol) is the primary network protocol used on the Internet, developed in the 1970s. On the Internet and many other networks, IP is often used together with the Transport Control Protocol (TCP) and referred to interchangeably as TCP/IP.IP supports unique addressing for computers on a network. Most networks use the Internet Protocol version 4 (IPv4) standard that features IP addresses four bytes (32 bits) in length. The newer Internet Protocol version 6 (IPv6) standard features addresses 16 bytes (128 bits) in length. • Data on an Internet Protocol network is organized into packets. Each IP packet includes both a header (that specifies source, destination, and other information about the data) and the message data itself. • IP functions at layer 3 of the OSI model. It can therefore run on top of different data link interfaces including Ethernet and Wi-Fi. • Also Known As: Internet Protocol
Networking Terms (The Short List) • Intranetis the generic term for a collection of private computer networks within an organization. An intranet uses network technologies as a tool to facilitate communication between people or work groups to improve the data sharing capability and overall knowledge base of an organization's employees.Intranets utilize standard network hardware and software technologies like Ethernet, WiFi, TCP/IP, Web browsers and Web servers. An organization's intranet typically includes Internet access but is firewalled so that its computers cannot be reached directly from the outside. • A common extension to intranets, called extranets, opens this firewall to provide controlled access to outsiders. • Many schools and non-profit groups have deployed them, but an intranet is still seen primarily as a corporate productivity tool. A simple intranet consists of an internal email system and perhaps a message board service. More sophisticated intranets include Web sites and databases containing company news, forms, and personnel information. Besides email and groupware applications, an intranet generally incorporates internal Web sites, documents, and/or databases. • The business value of intranet solutions is generally accepted in larger corporations, but their worth has proven very difficult to quantify in terms of time saved or return on investment. • Also Known As: corporate portal, private business network
Networking Terms (The Short List) • IPv6 is the next generation protocol for Internet networking. IPv6 expands on the current Internet Protocol standard known as IPv4. Compared to IPv4, IPv6 offers better addressing, security and other features to support large worldwide networks.In IPv6, IP addresses change from the current 32-bit standard and dotted decimal notation to a new 128-bit address system. IPv6 addresses remain backward compatible with IPv4 addresses. For example, the IPv4 address "192.168.100.32" may appear in IPv6 notation as "0000:0000:0000:0000:0000:0000:C0A8:6420" or "::C0A8:6420".The most obvious benefit of IPv6 is the exponentially greater number of IP addresses it can support compared to IPv4. Many countries outside the U.S. suffer from a shortage of IP addresses today. Because IPv6 and IPv4 protocols coexist, those locales with an address shortage can easily deploy new IPv6 networks that work with the rest of the Internet. Experts believe it will take many more years before all networks fully change over to IPv6.Other benefits of IPv6 are less obvious but equally important. The internals of the IPv6 protocol have been designed with scalability and extensibility in mind. This will allow many different kinds of devices besides PCs, like cell phones and home appliances, to more easily join the Internet in future. • Also Known As: IPng (Internet Protocol Next Generation)
Networking Terms (The Short List) • An IP addressis a binary number that uniquely identifies computers and other devices on a TCP/IPnetwork.An IP address can be private - for use on a local area network (LAN) - or public - for use on the Internet or other wide area network (WAN). IP addresses can be determined statically - assigned to a computer by a system administrator - or dynamically - assigned by another device on the network on demand. • → More - What Is a Public IP Address?, What Is a Private IP Address?Two IP addressing standards are in use today. The IPv4 standard is most familiar to people and supported everywhere on the Internet, but the newer IPv6 standard is gradually replacing it. IPv4 addresses consist of four bytes (32 bits), while IPv6 addresses are 16 bytes (128 bits) long. • → More - Internet Protocol Address NotationA network administrator sets up the addressing scheme for an IP network. When troubleshooting network problems, users sometimes also need to be familiar with how IP addresses work.
Networking Terms (The Short List) • ISDN is a network technology that supports digital transfer of simultaneous voice and data traffic. Similar to DSL in this respect, an ISDN Internet service works over ordinary telephone lines. ISDN Internet service generally supports data rates of 128 Kbps.ISDN emerged as an alternative to traditional dialup networking during the 1990s. The relatively high cost of ISDN service, though, limited its popularity with residential customers at the outset. More recently, the much higher network speeds supported by newer broadband technologies like DSL have drawn many consumers away from ISDN service. • ISDN technology today has limited applications as a networking solution. Some customers who live in rural areas of the U.S. subscribe to ISDN Internet as an alternative to satellite Internet. ISDN phone service also remains fairly common in some European countries. • Also Known As: Integrated Services Digital Network
Networking Terms (The Short List) • An ISP is a company that supplies Internet connectivity to home and business customers. ISPs support one or more forms of Internet access, ranging from traditional modem dial-up to DSL and cable modem broadband service to dedicated T1/T3 lines.More recently, wireless Internet service providers or WISPs have emerged that offer Internet access through wireless LAN or wireless broadband networks. • In addition to basic connectivity, many ISPs also offer related Internet services like email, Web hosting and access to software tools. • A few companies also offer free ISP service to those who need occasional Internet connectivity. These free offerings feature limited connect time and are often bundled with some other product or service.
Networking Terms (The Short List) • A local area network (LAN) supplies networking capability to a group of computers in close proximity to each other such as in an office building, a school, or a home. A LAN is useful for sharing resources like files, printers, games or other applications. A LAN in turn often connects to other LANs, and to the Internet or other WAN.Most local area networks are built with relatively inexpensive hardware such as Ethernet cables, network adapters, and hubs. Wireless LAN and other more advanced LAN hardware options also exist. • Specialized operating system software may be used to configure a local area network. For example, most flavors of Microsoft Windows provide a software package called Internet Connection Sharing (ICS) that supports controlled access to LAN resources. • The term LAN party refers to a multiplayer gaming event where participants bring their own computers and build a temporary LAN. • Also Known As: local area network
Networking Terms (The Short List) • Media Access Control (MAC) technology provides unique identification and access control for computers on an Internet Protocol (IP) network. In wireless networking, MAC is the radio control protocol on the wireless network adapter. Media Access Control works at the lower sublayer of the data link layer (Layer 2) of the OSI model.MAC Addresses • Media Access Control assigns a unique number to each IP network adapter called the MAC address. A MAC address is 48 bits long. The MAC address is commonly written as a sequence of 12 hexadecimal digits as follows: • 48-3F-0A-91-00-BC • MAC addresses are uniquely set by the network adapter manufacturer and are sometimes called physical addresses. The first six hexadecimal digits of the address correspond to a manufacturer's unique identifier, while the last six digits correspond to the device's serial number. MAC addresses map to logical IP addresses through the Address Resolution Protocol (ARP).Some Internet service providers track the MAC address of a home router for security purposes. Many routers support a process called cloning that allows the MAC address to be simulated so that it matches one the service provider is expecting. This allows households to change their router (and their real MAC address) without having to notify the provider.
Networking Terms (The Short List) • MIMO is a method of utilizing multiple radio antennas for wireless network communications. Some newer Wi-Fi routers utilize MIMO technology, enhancing their performance compared to single-antenna routers.MIMO-based Wi-Fi routers utilize the same network protocols and signal ranges that non-MIMO routers do. The MIMO products achieve higher performance by more aggressively transmitting and receiving data over Wi-Fi channels. MIMO signaling technology can increase network bandwidth, range and reliability at the potential cost of interfering with other wireless equipment. • The specific number of antennas utilized in a MIMO Wi-Fi router can vary. Typical MIMO routers contain three or four antennas instead of the single antenna that is standard in all earlier forms of consumer Wi-Fi routers. • MIMO is a key element of the 802.11n Wi-Fi networking standard. • Also Known As: Multiple-Input Multiple-Output
Networking Terms (The Short List) • NAS allows files to be stored and retrieved across a computer network. A NAS includes a dedicated hardware device often called the head that connects to a local area network (usually via Ethernet). This NAS "server" authenticates clients and manages file operations in much the same manner as traditional file servers, through well-established network protocols like NFS and CIFS/SMB. NAS systems attempt to reduce the cost associated with traditional file servers. Rather than utilize general-purpose computer hardware and a full-featured network operating system (NOS) like NetWare, NAS devices generally run an embedded operating system on simplified hardware. NAS boxes support hard drives, and sometimes tape drives, but lack peripherals like a monitor or keyboard. Designed specifically for network storage, a NAS tends to be easier to manage than a file server. • The term "NAS" is often confused with the related term "SAN" (Storage Area Network). In a nutshell, NAS devices are just one type of entity that can exist on a SAN. • Also Known As: Network Attached Storage
Networking Terms (The Short List) • NAT allows an Internet Protocol (IP) network to maintain public IP addresses separately from private IP addresses. NAT is a popular technology for Internet connection sharing. It is also sometimes used in server load balancing applications on corporate networks.In it's most common configuration, NAT maps all of the private IP addresses on a home network to the single IP address supplied by an Internet Service Provider (ISP). This allows computers on the home LAN to share a single Internet connection. Additionally, it enhances home network security by limiting the access of external computers into the home IP network space. • NAT works by snooping both incoming and outgoing IP datagrams. As needed, it modifies the source or destination address in the IP header (and the affected checksums) to reflect the configured address mapping. NAT technically supports either fixed or dynamic mappings of one or more internal and external IP addresses. • NAT functionality is usually found on routers and other gateway devices at the network boundary. • NAT can also be implemented entirely in software. Microsoft's Internet Connection Sharing (ICS), for example, adds NAT support to the Windows operating system. • By itself, NAT does not provide all the features of a true firewall, but it is often used on servers that feature other firewall and antivirus support. NAT was designed originally to conserve public Internet address space. Internet RFC 1631 contains the basic NAT specification. • Also Known As: Network Address Translation
Networking Terms (The Short List) • Anoctetrepresents any eight-bit quantity. By definition, octets range in mathematical value from 0 (zero) to 255. Typically in computer networking, an octet is the same as a byte. However, the term "octet" came into existence because historically some computer systems did not represent a byte as eight bits; octets and bytes are *not* the same on such systems. • Octets most commonly refers to any of the four bytes of an IPv4 address. In dotted-decimal notation, an IP address appears as follows - • [ octet ] . [ octet ] . [ octet ] . [ octet ] • like this: 192 . 168 . 0. 1 • In Web browsers, the MIME type "application/octet-stream" refers to a generic HTTP byte stream.
Networking Terms (The Short List) • The OSI modeldefines internetworking in terms of a vertical stack of seven layers. The upper layers of the OSI model represent software that implements network services like encryption and connection management. The lower layers of the OSI model implement more primitive, hardware-oriented functions like routing, addressing, and flow control. In the OSI model, data communication starts with the top layer at the sending side, travels down the OSI model stack to the bottom layer, then traveses the network connection to the bottom layer on the receiving side, and up its OSI model stack. • The OSI model was introduced in 1984. Although it was designed to be an abstract model, the OSI model remains a practical framework for today's key network technologies like Ethernet and protocols like IP. • Also Known As: Open Systems Interconnection (OSI) reference model, OSI seven layer model • Examples: • Internet Protocol (IP) corresponds to the Network layer of the OSI model, layer three. TCP and UDP correspond to OSI model layer four, the Transport layer. Lower layers of the OSI model are represented by technologies like Ethernet. Higher layers of the OSI model are represented by application protocols like TCP and UDP.
Networking Terms (The Short List) • Pingis the name of a standard software utility (tool) used to test network connections. It can be used to determine if a remote device (such as Web or game server) can be reached across the network and, if so, the connection's latency. Ping tools are part of Windows, Mac OS X and Linux as well as some routers and game consoles.Most ping tools use Internet Control Message Protocol (ICMP). They send request messages to a target network address at periodic intervals and measure the time it takes for a response message to arrive. These tools typically support options like • how many times to send requests • how large of a request message to send • how long to wait for each reply • The output of ping varies depending on the tool. Standard results includes • IP address of the responding computer • length of time (in milliseconds) between sending the request and receiving the response • an indication of how many network hops between the requesting and responding computers • error messages if the target computer did not respond • Also Known As: Packet Internet Gopher
Networking Terms (The Short List) • RJ45 is a standard type of connector for network cables. RJ45 connectors are most commonly seen with Ethernet cables and networks.RJ45 connectors feature eight pins to which the wire strands of a cable interface electrically. Standard RJ-45 pinouts define the arrangement of the individual wires needed when attaching connectors to a cable. • Several other kinds of connectors closely resemble RJ45 and can be easily confused for each other. The RJ-11 connectors used with telephone cables, for example, are only slightly smaller (narrower) than RJ-45 connectors. • Also Known As: Registered Jack 45
Networking Terms (The Short List) • : Routersare small physical devices that join multiple networks together. Technically, a router is a Layer 3 gateway device, meaning that it connects two or more networks and that the router operates at the network layer of the OSImodel.Home networks typically use a wireless or wired Internet Protocol (IP) router, IP being the most common OSI network layer protocol. An IP router such as a DSL or cable modem broadband router joins the home's local area network (LAN) to the wide-area network (WAN) of the Internet. • By maintaining configuration information in a piece of storage called the routing table, wired or wireless routers also have the ability to filter traffic, either incoming or outgoing, based on the IP addresses of senders and receivers. Some routers allow a network administrator to update the routing table from a Web browser interface. Broadband routers combine the functions of a router with those of a network switch and a firewall in a single unit.
Networking Terms (The Short List) • A network serveris a computer designed to process requests and deliver data to other (client) computers over a local network or the Internet.Network servers typically are configured with additional processing, memory and storage capacity to handle the load of servicing clients. Common types of network servers include: • Web servers • proxy servers • FTP servers • online game servers • Numerous systems use this client / server networking model including Web sites and email services. An alternative model, peer-to-peer networking enables all computers to act as either a server or client as needed.
Networking Terms (The Short List) • An SSID is the name of a wireless local area network (WLAN). All wireless devices on a WLAN must employ the same SSID in order to communicate with each other.The SSID on wireless clients can be set either manually, by entering the SSID into the client network settings, or automatically, by leaving the SSID unspecified or blank. A network administrator often uses a public SSID, that is set on the access point and broadcast to all wireless devices in range. Some newer wireless access points disable the automatic SSID broadcast feature in an attempt to improve network security. • SSIDs are case sensitive text strings. The SSID is a sequence of alphanumeric characters (letters or numbers). SSIDs have a maximum length of 32 characters. • See also - What is a Network Name? • Also Known As: Service Set Identifier, Network Name
Networking Terms (The Short List) • Secure Sockets Layer (SSL) technology is a standard for encrypted client/server network connections. SSL helps to improve on the safety of Internet communications. It is commonly used for online shopping and other private financial transactions.As a network protocol, SSL runs on top of TCP/IP. SSL utilizes network security techniques including public keys, symmetric keys, and certificates. • Also Known As: Secure Sockets Layer
Networking Terms (The Short List) • A subnet is a logical grouping of connected network devices. Nodes on a subnet tend to be located in close physical proximity to each other on a LAN.Network designers employ subnets as a way to partition networks into logical segments for greater ease of administration. When subnets are properly implemented, both the performance and security of networks can be improved. • In Internet Protocol (IP) networking, devices on a subnet share contiguous ranges of IP address numbers. A mask (known as the subnet mask or network mask) defines the boundaries of an IP subnet. The correspondence between subnet masks and IP address ranges follows defined mathematical formulas. IT professionals use subnet calculators to map between masks and addresses. • Also Known As: subnetwork
Networking Terms (The Short List) • A network switchis a small hardware device that joins multiple computers together within one local area network (LAN). Technically, network switches operate at layer two (Data Link Layer) of the OSI model.Network switches appear nearly identical to network hubs, but a switch generally contains more intelligence (and a slightly higher price tag) than a hub. Unlike hubs, network switches are capable of inspecting data packets as they are received, determining the source and destination device of each packet, and forwarding them appropriately. By delivering messages only to the connected device intended, a network switch conserves network bandwidth and offers generally better performance than a hub. • As with hubs, Ethernet implementations of network switches are the most common. Mainstream Ethernet network switches support either 10/100 Mbps Fast Ethernet or Gigabit Ethernet (10/100/1000) standards. • Different models of network switches support differing numbers of connected devices. Most consumer-grade network switches provide either four or eight connections for Ethernet devices. Switches can be connected to each other, a so-called daisy chaining method to add progressively larger number of devices to a LAN.
Networking Terms (The Short List) • SNMP is a standard TCP/IP protocol for network management. Network administrators use SNMP to monitor and map network availability, performance, and error rates.Using SNMP • To work with SNMP, network devices utilize a distributed data store called the Management Information Base (MIB). All SNMP compliant devices contain a MIB which supplies the pertinent attributes of a device. Some attributes are fixed (hard-coded) in the MIB while others are dynamic values calculated by agent software running on the device.Enterprise network management software, such as Tivoli and HP OpenView, uses SNMP commands to read and write data in each device MIB. 'Get' commands typically retrieve data values, while 'Set' commands typically initiate some action on the device. For example, a system reboot script is often implemented in management software by defining a particular MIB attribute and issuing an SNMP Set from the manager software that writes a "reboot" value into that attribute.
Networking Terms (The Short List) • Satellite Internetis a form of high-speed Internet service. Satellite Internet services utilize telecommunications satellites in Earth orbit to provide Internet access to consumers. Satellite Internet service covers areas where DSL and cable access is unavailable. Satellite offers less network bandwidth compared to DSL or cable, however. In addition, the long delays required to transmit data between the satellite and the ground stations tend to create high network latency, causing a sluggish performance experience in some cases. Network applications like VPN and online gaming may not function properly over satellite Internet connections due to these latency issues. • Older residential satellite Internet services supported only "one-way" downloads over the satellite link, requiring a telephone modem for uploading. All newer satellite services support full "two-way" satellite links. • Satellite Internet service does not necessary utilitizeWiMax. WiMax technology supplies one method to deliver high-speed Internet service over wireless links, but satellite providers may implement their systems differently.
Networking Terms (The Short List) • Transmission Control Protocol (TCP) and Internet Protocol (IP) are two distinct network protocols, technically speaking. TCP and IP are so commonly used together, however, that TCP/IP has become standard terminology to refer to either or both of the protocols.IP corresponds to the Network layer (Layer 3) in the OSI model, whereas TCP corresponds to the Transport layer (Layer 4) in OSI. In other words, the term TCP/IP refers to network communications where the TCP transport is used to deliver data across IP networks. • The average person on the Internet works in a predominately TCP/IP environment. Web browsers, for example, use TCP/IP to communicate with Web servers. • Also Known As: Transmission Control Protocol / Internet Protocol
Networking Terms (The Short List) • UDP (User Datagram Protocol) is a simple OSI transport layer protocol for client/server network applications based on Internet Protocol (IP). UDP is the main alternative to TCP and one of the oldest network protocols in existence, introduced in 1980.UDP is often used in videoconferencing applications or computer games specially tuned for real-time performance. To achieve higher performance, the protocol allows individual packets to be dropped (with no retries) and UDP packets to be received in a different order than they were sent as dictated by the application. • UDP Datagrams • UDP network traffic is organized in the form of datagrams. A datagram comprises one message unit. The first eight (8) bytes of a datagram contain header information and the remaining bytes contain message data.A UDP datagram header consists of four (4) fields of two bytes each: • source port number • destination port number • datagram size • checksum • UDP port numbers allow different applications to maintain their own channels for data similar to TCP. UDP port headers are two bytes long; therefore, valid UDP port numbers range from 0 to 65535.The UDP datagram size is a count of the total number of bytes contained in header and data sections. As the header length is a fixed size, this field effectively tracks the length of the variable-sized data portion (sometimes called payload). The size of datagrams varies depending on the operating environment but has a maximum of 65535 bytes. • UDP checksums protect message data from tampering. The checksum value represents an encoding of the datagram data calculated first by the sender and later by the receiver. Should an individual datagram be tampered with or get corrupted during transmission, the UDP protocol detects a checksum calculation mismatch. In UDP, checksumming is optional as opposed to TCP where checksums are mandatory.
Networking Terms (The Short List) • UPnP is a technology framework for simplifying the connection of network devices. The UPnP Forum is an industry body coordinating activities related to UPnP standardization and adoption.UPnP is based on Internet Protocol (IP) addressing and Dynamic Host Configuration Protocol (DHCP). UPnP does not require any particular type of network connection; it works with Ethernet, Wi-Fi, Bluetooth and other physical media. UPnP also is designed to work across many different types of network devices and operating systems. • Many home network routers offer UPnP support. UPnP is not related to the older "Plug and Play" industry initatives for connecting periperhal devices to PCs.
Networking Terms (The Short List) • URLstands for Uniform Resource Locator. A URL is a formatted text string used by Web browsers, email clients and other software to identify a network resource on the Internet. Network resources are files that can be plain Web pages, other text documents, graphics, or programs.URL strings consist of three parts (substrings): • 1. network protocol2. host name or address3. file or resource location • These substrings are separated by special characters as follows: protocol :// host / location